In the 40 years since the Paris Peace Accords, millions of words have been written about the lessons of Vietnam – the traumatic American military intervention that escalated year by year, cost hundreds of thousands of lives on both sides, and deeply divided the American people.

Shortly after the fall of Saigon, the American diplomat and historian George Kennan saw the lessons of Vietnam as “few and plain: not to be hypnotized by the word ‘communism’ and not to mess into other people’s civil wars where there is no substantial American strategic interest at stake.” Other thinkers have noted the perils of superpower hubris and the inherent problems democracies have with protracted, inconclusive conflicts.

In 1987, David Petraeus, an Army major at the time, did his doctoral dissertation on the lessons of Vietnam, noting, among other things, that “when it comes to intervention, time and patience are not American virtues in abundant supply.” Two decades after his dissertation, as time and patience were running out in Iraq and Afghanistan, it fell to then-General Petraeus to hasten the conclusion of those conflicts.

Historians are now analyzing those wars for their own lessons, which will probably echo Vietnam’s (possibly with the word “terrorism” substituted for the word “communism”) and contain the same caution about determining the importance of American strategic interests before committing combat troops.

Amid all the treatises about postwar geopolitics, popular opinion, and national credibility, the humans caught up in the wars are usually relegated to footnotes. The young men and women who leave home to fight for a nation’s strategic interests are expected to keep the war “over there” when they come home.

In a Monitor cover story, Nissa Rhee focuses on Americans who served in Vietnam in the 1960s and ’70s and who have been returning to the country to clean up old battlefields and campaign for American aid to help Vietnam cope with lingering problems such as the aftermath of the use of Agent Orange. The Vietnamese have always been surprisingly cordial to these onetime enemies.

While a nation may see a war as a chapter in a history book, to veterans war is personal. It embeds itself in a veteran’s life. “I tell people that I was born in Vietnam,” one veteran told Nissa. “Everything I’ve ever done since leaving Vietnam has been affected by my time here.”

Few of us can know what individual veterans have gone through. My dad, for instance, served in North Africa, Europe, and the Pacific during World War II and later in the Korean War. After he retired, he would often regale his children with war stories over Saturday morning pancakes. To kids, war can seem interesting, vivid, even fun. We didn’t know it then, but it eventually became clear that there were stories he wasn’t telling us, that he would never tell us. In that, he was like most veterans who mentally wall off portions of what they experienced.

Veterans do that because they don’t want to bring the war home, because home should be the antithesis of war. The veterans in our cover story take that gallantry to a new level. They are not just retired sightseers reliving the days when they were soldiers once and young. They are a present-day army trying to make a difference where they once made a war. To these old warriors, “over here” and “over there” are not separate places.

John Yemma is editor of the Monitor. He can be reached at editor@csmonitor.com.